6 Appendix A: Product Behavior

The information in this specification is applicable to the following Microsoft products or supplemental software. References to product versions include updates to those products.

  • Windows XP operating system

  • Windows Server 2003 operating system

  • Windows Server 2003 R2 operating system

  • Windows Vista operating system

  • Windows Server 2008 operating system

  • Windows 7 operating system

  • Windows Server 2008 R2 operating system

  • Windows 8 operating system

  • Windows Server 2012 operating system

  • Windows 8.1 operating system

  • Windows Server 2012 R2 operating system

  • Windows 10 operating system

  • Windows Server 2016 operating system

  • Windows Server 2019 operating system

  • Windows Server 2022 operating system

  • Windows 11 operating system

  • Windows Server 2025 operating system

Exceptions, if any, are noted in this section. If an update version, service pack or Knowledge Base (KB) number appears with a product name, the behavior changed in that update. The new behavior also applies to subsequent updates unless otherwise specified. If a product edition appears with the product version, behavior is different in that product edition.

Unless otherwise specified, any statement of optional behavior in this specification that is prescribed using the terms "SHOULD" or "SHOULD NOT" implies product behavior in accordance with the SHOULD or SHOULD NOT prescription. Unless otherwise specified, the term "MAY" implies that the product does not follow the prescription.

<1> Section 1.5: Windows POP3 server and POP3 client use the Security Support Provider Interface (SSPI) to obtain and process NTLM messages. For more information about the SSPI, see [SSPI].

<2> Section 1.6: The POP3 Server component shipped only with Windows Server 2003 and Windows Server 2003 R2. Other versions of Windows (both client and server) that use either Outlook Express or the Windows Mail Client use the client side portion of this protocol.

<3> Section 2.2.1: In Windows, the POP3_AUTH_NTLM_Cancelled_Response is "-ERR The AUTH protocol exchange was canceled by the client".